IP Library Granted Patent US 12,359,834
Granted Patent B2
US 12,359,834 · App. 18/087,472 · Granted Jul 15, 2025

System and method for HVAC fan control

Inventors: Wade Ferkey (Madison, WI); Stephen Moon (Madison, WI)
Assignee: Research Products Corporation
F24F11/72F24F11/0001F24F11/80F24F2110/10F24F2110/20
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Quick Facts
Patent No.
US 12,359,834
App. No.
18/087,472
Filed
Dec 22, 2022
Granted
Jul 15, 2025
Kind
B2
Examiner
MA, KUN KAI
Art Unit
3763
USPC
236/1B
Abstract

An HVAC system includes a first air quality sensor and a second air quality sensor. The system contains a controller which calculates a differential between the first air quality sensor and the second air quality sensor. The differential is compared to a threshold. If the threshold is satisfied, a fan is engaged which may, reducing the air quality differential as sensed by the first and second air quality sensor.

Claims (66)

1. An HVAC system, comprising:

a first temperature sensor configured to detect a first temperature of a first area;

a second temperature sensor configured to detect a second temperature of a second area;

a controller configured to:

calculate a first temperature differential between the first area and the second area;

determine whether a threshold is satisfied based on a comparison of the first temperature differential to a first threshold differential; and

responsive to the satisfaction of the threshold, cause activation of a fan to circulate air through the first and second areas; and

the fan, wherein the fan is configured to circulate the air through the first and second areas in response to a request from the controller, wherein the first threshold differential is determined based on a control state.

2. The HVAC system of claim 1 wherein:

the first temperature sensor is configured to detect a third temperature of the first area;

the second temperature is configured to detect a fourth temperature of the second area; and

the controller is configured to:

calculate a second temperature differential between the first area and the second area, based on the third temperature and the fourth temperature;

compare the second temperature differential to a second threshold differential;

responsive to the second temperature differential failing to satisfy the threshold, maintain a non-operating state of the fan;

compare the third temperature to a set-point; and

enable at least one of a furnace or air conditioner, based on the comparison of the third temperature to the set-point.

3. The HVAC system of claim 1 wherein the HVAC system comprises a plurality of zones and a plurality of dampers to control airflow to respective zone of the plurality of zones, and wherein each area corresponds to a respective area within a particular zone of the plurality of zones.

4. The HVAC system of claim 1 wherein the control state is one of a time of day, a sensed occupancy, or an energy cost.

5. The HVAC system of claim 1 wherein the controller is configured to:

receive a first control state value;

determine a progress towards the threshold based on calculating the second threshold differential based on the first control state value, and comparing a second temperature differential to the first threshold differential;

receive a second control state value; and

determine that the threshold has been satisfied based on a calculation of the first threshold differential, based on a cumulative contribution of the first and second control state values, and based on comparing the first temperature differential to the first threshold differential.

6. The HVAC system of claim 1 wherein the threshold is determined based on a humidity level.

7. A method of climate control comprising:

sensing a first set of temperatures of a plurality of areas;

calculating a first temperature differential between the first set of temperatures;

comparing the first temperature differential to a first threshold differential; and

engaging a fan based on a comparison of the first temperature differential to the first threshold differential;

sensing a second set of temperatures at the plurality of areas while the fan is engaged;

calculating a second temperature differential between the second set of temperatures;

comparing the second temperature differential to a second threshold differential; and

disengaging the fan based on the comparison of the second temperature differential to the second threshold differential.

8. The method of claim 7 , further comprising calling for heating or calling for cooling based on at least one of:

an average temperature of the plurality of areas; or

the completion of a fixed period of fan operation which fails to satisfy a temperature set-point in at least one of the plurality of areas.

9. The method of claim 7 wherein engaging the fan depends on a control state wherein the control state is one of a time of day, a sensed occupancy, or an energy cost.

10. The method of claim 7 wherein the first threshold differential is determined based on a particulate count.

11. A method of climate control comprising:

sensing a first set of temperatures of a plurality of areas;

calculating a first temperature differential between the first set of temperatures;

comparing the first temperature differential to a first threshold differential; and

engaging a fan based on a comparison of the first temperature differential to the first threshold differential, wherein the first threshold differential is determined based on at least one of a humidity level or a particulate count.

12. An HVAC controller comprising a non-transitory computer-readable medium having instructions stored thereon; and a processor configured to execute the instructions to:

receive a first temperature measurement from a first temperature sensor of a first area;

receive a second temperature measurement from a second temperature sensor of a second area;

calculate a first temperature differential between the first area and the second area;

determine whether the first temperature differential satisfies a threshold based on a comparison of the first temperature differential to a first threshold differential;

generate a first control signal to enable a fan, based on the satisfaction of the threshold;

receive a third temperature measurement of the first area from the first temperature sensor;

receive a fourth temperature measurement of the second area from the second temperature sensor;

calculate a second temperature differential between the first area and the second area, based on the third temperature and the fourth temperature;

compare the second temperature differential to a second threshold differential;

responsive to the second temperature differential failing to satisfy the threshold, maintain the first control signal in a non-operating-state;

compare the third temperature to a set-point; and

output a second control signal, based on the comparison of the third temperature to the set-point, to a furnace or air conditioner.

13. The HVAC controller of claim 12 wherein the controller is not configured to activate a furnace or an air conditioner.

14. The HVAC controller of claim 12 wherein the threshold is based on a control state.

15. The HVAC controller of claim 14 wherein the control state is one of a time of day, a sensed occupancy, or an energy cost.

16. The HVAC controller of claim 14 wherein the controller is configured to:

receive a first control state value;

determine a progress towards the threshold based on calculating a second threshold differential based on the first control state value, and comparing a second temperature differential to the first threshold differential;

receive a second control state value; and

determine that the threshold has been satisfied based on a calculation of the first threshold differential, based on a cumulative contribution of the first and second control state values, and comparing the first temperature differential to the first threshold differential.

17. The HVAC controller of claim 12 wherein the threshold is based on a humidity level.

Assignments (4)
ASSIGNMENT OF PATENT SECURITY AGREEMENT, RECORDED ON OCTOBER 15, 2025 AT REEL/FRAME 73109/0707 Recorded Jul 16, 2026
From: GOLDMAN SACHS BANK USA, AS EXISTING AGENT
To: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS SUCCESSOR AGENT
Reel/Frame 075998/0444 →
PATENT SECURITY AGREEMENT Recorded Oct 15, 2025
From: RESEARCH PRODUCTS CORPORATION; DRI-STEEM CORPORATION; EWC CONTROLS, LLC
To: GOLDMAN SACHS BANK USA, AS COLLATERAL AGENT
Reel/Frame 073109/0707 →
SECURITY INTEREST Recorded Oct 6, 2025
From: RESEARCH PRODUCTS CORPORATION; DRI-STEEM CORPORATION; EWC CONTROLS, LLC
To: U.S. BANK NATIONAL ASSOCIATION
Reel/Frame 073007/0564 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Dec 27, 2022
From: FERKEY, WADE; MOON, STEPHEN
To: RESEARCH PRODUCTS CORPORATION
Reel/Frame 062210/0419 →
Continuity (2)
Provisional Application 63296307 · Jan 4, 2022
Related Publication 20230213233A1 · Jul 6, 2023
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